35 research outputs found
Theoretical Characterization of the Interface in a Nonequilibrium Lattice System
The influence of nonequilibrium bulk conditions on the properties of the
interfaces exhibited by a kinetic Ising--like model system with nonequilibrium
steady states is studied. The system is maintained out of equilibrium by
perturbing the familiar spin--flip dynamics at temperature T with
completely--random flips; one may interpret these as ideally simulating some
(dynamic) impurities. We find evidence that, in the present case, the
nonequilibrium mechanism adds to the basic thermal one resulting on a
renormalization of microscopic parameters such as the probability of
interfacial broken bonds. On this assumption, we develop theory for the
nonequilibrium "surface tension", which happens to show a non--monotonous
behavior with a maximum at some finite T. It ensues, in full agreement with
Monte Carlo simulations, that interface fluctuations differ qualitatively from
the equilibrium case, e.g., the interface remains rough at zero--T. We discuss
on some consequences of these facts for nucleation theory, and make some
explicit predictions concerning the nonequilibrium droplet structure.Comment: 10 pages, 7 figures, submitted to Phys. Re
A lattice model for the line tension of a sessile drop
Within a semi--infinite thre--dimensional lattice gas model describing the
coexistence of two phases on a substrate, we study, by cluster expansion
techniques, the free energy (line tension) associated with the contact line
between the two phases and the substrate. We show that this line tension, is
given at low temperature by a convergent series whose leading term is negative,
and equals 0 at zero temperature
Random walks in space time mixing environments
We prove that random walks in random environments, that are exponentially
mixing in space and time, are almost surely diffusive, in the sense that their
scaling limit is given by the Wiener measure.Comment: 28 page